Why are you putting the form into a table? You shouldn't use tables for layout, that is what CSS is for.
As far as having excess white space below the form, you have set height to 972 on several places in your page. You will just have to reduce those heights.
The horizontal white space is caused by your loggia.css #content section. You have the margin set to 0 0 0 250px; Just reduce the 250px margin to something lower and the white space will go away on the left.